FAT-fs (loop5): Directory bread(block 112) failed
FAT-fs (loop5): Directory bread(block 112) failed
FAT-fs (loop5): Directory bread(block 112) failed
INFO: task syz-executor5:11979 blocked for more than 120 seconds.
      Not tainted 4.9.103-g0cecdf8 #35
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor5   D27240 11979   3775 0x00000004
 ffff8801cd019800 ffff8801d6eb3480 ffff8801cfa99500 ffff8801ce3be000
 ffff8801db321c18 ffff8801cbfafc10 ffffffff839e711d ffff880186f61188
 0000000000000000 0000000000000000 0000000000000000 ffff8801db3224e8
Call Trace:
 [<ffffffff839e871f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f2b44>] rwsem_down_read_failed+0x1e4/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81ee7758>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff839f1a72>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff839f1a72>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff8157c891>] iterate_supers+0xe1/0x260 fs/super.c:591
 [<ffffffff8161a6b2>] sys_sync+0xa2/0x170 fs/sync.c:112
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f8013>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136688c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136688c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425e10>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3658:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f61c2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211f1d2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor5/11979:
 #0:  (&type->s_umount_key#36){++++..}, at: [<ffffffff8157c891>] iterate_supers+0xe1/0x260 fs/super.c:591
1 lock held by syz-executor5/12000:
 #0:  (&type->s_umount_key#36){++++..}, at: [<ffffffff8157c891>] iterate_supers+0xe1/0x260 fs/super.c:591

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.103-g0cecdf8 #35
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d857fd08 ffffffff81eb34a9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9590 ffff8801d857fd40
 ffffffff81ebe7a7 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb34a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb34a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebe7a7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebe73a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9694>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366e24>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366e24>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366e24>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366e24>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119cead>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f81dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 11908 Comm: syz-executor0 Not tainted 4.9.103-g0cecdf8 #35
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801ce3be000 task.stack: ffff880190c20000
RIP: 0010:[<ffffffff8127c4cc>] 
c [<ffffffff8127c4cc>] __rcu_read_unlock+0x2c/0x1a0 kernel/rcu/update.c:218
RSP: 0018:ffff880190c274f8  EFLAGS: 00000a02
RAX: 0000000000000000 RBX: ffff8801ce3be000 RCX: ffffc9000011f000
RDX: 1ffff10039c77c7c RSI: ffffffff81438d20 RDI: ffffffff84431400
RBP: ffff880190c27508 R08: ffff8801ce3be910 R09: 0000000000000001
R10: ffff8801ce3be000 R11: 1ffff10039c77d1d R12: ffff8801ce3be3e0
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8801d61cc888
FS:  00007f1669978700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe4e9d0da0 CR3: 00000001c86fa000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d61cc888
c 0000000000000000
c ffff880190c27570
c ffffffff81438d25
c
 ffffffff81438c00
c ffffed0039c77d18
c ffff8801ce3be8c8
c 0000000000000096
c
 ffff8801d61cc890
c 0000000000000000
c ffff8801d61cc888
c 0000000000000001
c
Call Trace:
 [<ffffffff81438d25>] rcu_read_unlock include/linux/rcupdate.h:930 [inline]
 [<ffffffff81438d25>] find_get_entry+0x125/0x540 mm/filemap.c:1132
 [<ffffffff8143a07b>] pagecache_get_page+0x4b/0x720 mm/filemap.c:1203
 [<ffffffff81623842>] find_get_page_flags include/linux/pagemap.h:264 [inline]
 [<ffffffff81623842>] __find_get_block_slow+0xc2/0x330 fs/buffer.c:212
 [<ffffffff81623dee>] __find_get_block+0x23e/0x4c0 fs/buffer.c:1360
 [<ffffffff81624bf9>] __getblk_slow fs/buffer.c:1101 [inline]
 [<ffffffff81624bf9>] __getblk_gfp+0x189/0x710 fs/buffer.c:1386
 [<ffffffff8162859d>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff818b6428>] sb_bread include/linux/buffer_head.h:300 [inline]
 [<ffffffff818b6428>] fat__get_entry+0x4c8/0x8f0 fs/fat/dir.c:100
 [<ffffffff818b90b1>] fat_get_entry fs/fat/dir.c:128 [inline]
 [<ffffffff818b90b1>] fat_get_short_entry+0x131/0x2a0 fs/fat/dir.c:876
 [<ffffffff818c1017>] fat_subdirs+0xc7/0x190 fs/fat/dir.c:942
 [<ffffffff818d1329>] fat_read_root fs/fat/inode.c:1402 [inline]
 [<ffffffff818d1329>] fat_fill_super+0x1cf9/0x3550 fs/fat/inode.c:1832
 [<ffffffff818d80e1>] vfat_fill_super+0x31/0x40 fs/fat/namei_vfat.c:1070
 [<ffffffff8157c007>] mount_bdev+0x2c7/0x390 fs/super.c:1100
 [<ffffffff818d80a4>] vfat_mount+0x34/0x40 fs/fat/namei_vfat.c:1077
 [<ffffffff8157dd8c>] mount_fs+0x28c/0x370 fs/super.c:1206
 [<ffffffff815dd331>] vfs_kern_mount.part.29+0xd1/0x3d0 fs/namespace.c:991
 [<ffffffff815e4c59>] vfs_kern_mount fs/namespace.c:973 [inline]
 [<ffffffff815e4c59>] do_new_mount fs/namespace.c:2513 [inline]
 [<ffffffff815e4c59>] do_mount+0x3c9/0x2740 fs/namespace.c:2835
 [<ffffffff815e79ae>] SYSC_mount fs/namespace.c:3051 [inline]
 [<ffffffff815e79ae>] SyS_mount+0xfe/0x110 fs/namespace.c:3028
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f8013>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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c